1. Field of the Invention
The invention relates to robotic autonomous equipment to perform maintenance work in wells (conduits) using the flow of preferably oil and gas through the conduit to aid in the movement and a control system that allows communication and coordination with an entire system of associated devices.
2. Description of the Related Art
The production of oil and gas from the reservoirs within earth requires the building of conduits for the transport of the oil and gas. These conduits are wells, pipelines, and risers and they convey the oil and gas to a desired location for distribution or processing. The hydrocarbon production system requires maintenance of the conduits and management of permanently emplaced tool to improve the production of hydrocarbons from the reservoir.
The production of hydrocarbons takes place over many years and the conduits (wells, pipelines, and risers) through which the oil and gas are conveyed deteriorate and the permanently emplaced equipment deteriorates during the operating life of the conduits. These systems are operated until they break at which time individual components, or the entire system, is replaced. Various operations are performed during the producing life of the wells, pipelines, or risers. Such operations generally require ceasing production of hydrocarbons through the conduits before any work can take place. The operations that are performed during the producing life of the wellbore include removing and replacing different types of devices, including flow control devices, sensors, packs, and seals. Remedial work takes place by shutting down production to move sliding sleeves, replace gas lift valves, testing zones, acquiring data by introducing sensors, repairs and replacement of production tubes and other components.
Once the production of hydrocarbons has ceased, downhole operations are performed by conveying a bottomhole assembly containing the tools required to perform the work. A rig is positioned at the wellhead to convey the bottomhole assembly to the desired work site using a conveying means attached to the rig which is typically a coiled tubing, jointed pipe, electric line, wire line, wire line and tractor device. Operation may include downhole tools using artificially based controls that are conveyed into the wellbore by a base unit from which the work unit detaches itself to perform a predetermined operation and then returns to the base unit to transfer data and recharged itself.
Certain wells are built to enable surface activated control of fluid control devices located in the wellbore and include permanent emplacement of hydraulic cables and wires by which to activate from the surface sleeves, chokes, packers or seals needed to open or close off production from different zones. Permanently emplace fiber optic cables may be used to continuously provide data to the surface control system on temperature and pressure from locations throughout the well.
U.S. Pat. No. 5,186,264 to du Chaffaut U.S. Pat. No. 5,316,094 to Pringle (Pringle '094) U.S. Pat. No. 5,373,898 to Pringle (Pringle '898) ad U.S. Pat. No. 5,394,951 to Pringle et al disclose certain structures for guiding downhole tools in wellbores. The du Chaffant patent discloses a device for guiding a drilling tool into the wellbore. The Pringle '094 patent discloses an orientation mandrel that is rotatable in an orientation body for providing rotational direction. Pringle '898 patent discloses a tool with an elongated circular body and fluid bore throughout.
Pringle et al patent discloses a bottomhole drilling assembly connectable to coiled tubing that is controlled from the surface.
Another series of patents disclose apparatus for moving through the interior of a pipe. These include U.S. patents to Hedgcoxe et al., U.S. Pat. No. 5,203,646 to Landsberger et al. and U.S. Pat. No. 5,392,715 to Pelrine. The Hedgcox et al. Patent discloses a robotic pipe crawling device with two three wheeled modules pivotally connected at their centers. Each module has only one idler wheel and two driven wheels, an idler yoke and a driveline yoke chassis with parallel, laterally placed, rectangular side plates. The idler side plates are pinned to the chassis and the drive wheels are rotably mounted one at each end a motor at each end of the chassis pivots the wheel independently into and out of a wheel engaging position n the interior of the pipe and a and a drive motor carried by the driveline yoke drives drive wheels in opposite directions to propel the device. A motor mounted within each idler yoke allows them to pivot independently of the driveline yoke. A swivel joint in the chassis midsection allows each end to rotate relative to each other. The chassis may be extended with additional driveline yokes. In addition to a straight traverse the device is capable of executing a “roll sequence” to change its orientation about its longitudinal axis, and “L”, “T”, and “Y” cornering sequences. Connected to a computer the device can “learn” a series of axis control sequences after being driven through the maneuvers manually.
The Landsberger et al Patent discloses an underwater robot that is employed to clean and/or inspect the inner surface of high flow rate pipes. The robot crawls along a cable positioned within the pipe to be inspected or cleaned. A plurality of guidance fins relies upon the flow of water through the pipe to position the robot as desired. Retractable legs can fix the robot at a location within the pipe for cleaning purposes. A water driven turbine can generate electricity for various motors, servos and other actuators contained on board the robot. The robot also can include wheel or pulley arrangements that further assist the robot in negotiating sharp corners or other obstructions.
The Pelrine Patent discloses an in pipe running robot with a vehicle body movable inside the pipe along a pipe axis. A pair of running devices is disposed in the front and rear positions of the vehicle body. Each running device has a pair of wheels secured to the opposite ends of an axe!. The wheel are steerable as a unit about the vertical axis of the vehicle body and have a center of steering thereof extending linearly in the fore and aft direction of the vehicle body. When the robot is caused to run in a circumferential direction inside in a pipe the vehicle body is set in a posture having the fore and aft direction inclined with respect to the pipe axis. The running devices are then set to posture for running in the circumferential direction. Thus, the running devices are driven to cause the vehicle body to run stably in the circumferential direction of the pipe.
Additionally, U.S. Pat. No. 5,291,112 to Karidis et al and U.S. Pat. No. 5,350,033 to Kraft disclose robotic devices with certain work elements. The Karidis et al. patent disclose robotic devices with certain work elements. The Karidis et a!. patent discloses a positioning apparatus and movement sensor in which positioned includes a first sensor having a curved corner reflector, a second section and a third section with an analog positioning sensitive photodiode. The second section includes light emitting diodes (LEDs) and photo detectors. Two LEDs and the photo detectors faced in the first direction toward the corner reflector. The third LED faces in a second direction different from the first direction toward the photosensitive photodiode. The second section can be mounted on an arm of the positioned and used in conjunction with the first and third sections to determine movement or position of that arm.
The Angle et al U.S. Pat. No. 5,947,213 and No. 6,026,911 and No. 6,112,809 disclose downhole tools using artificial intelligence based control concepts in which a problem is decomposed into a number of tasks achieving behaviors running in parallel. The system includes an electrically operated mobility platform to move the downhole tool and end work device to perform the desired work. The downhole tool contains an imaging device to provide pictures of the downhole environment. The data from the downhole tools is communicated to a surface computer, which controls the operation of the tool and displays pictures of the tool environment. Tactile sensors are used as imaging devices.
The downhole tool may be composed of a base unit and detachable work unit, which detaches and returns to the base unit to be recharged. A two-way telemetry system provides two-way communication between the downhole tool and the surface control unit via a wire line.
The Barrett et al U.S. Pat. No. 6,405,798 discloses downhole tools and apparatus for logging and/or remedial operations in a Wellbore in a hydrocarbon reservoir. The tool comprises an autonomous unit for measuring downhole conditions, preferably flow conditions. The autonomous unit comprises a means of locomotion, measurement, and a logic unit capable of making decisions based on at least two parameters. It can be separately attached to a wireline unit and connected to the surface or launched from the surface and preferably includes an active component for closing and/or breaking the connection.
The above noted patents and known prior art downhole tools (a) are dependent upon wireline hydraulic lines, electric lines, and fiber optic cable for two way communication between the downhole and the surface control unit (b) require communication of data from the downhole tool to a surface control to a surface computer, which controls the operation of the stationary or movable tool (c) do not have a program in the device which can control the work tool in the performance of the specific functions to perform specific types of work (c) only operate in the well, or conduit when production of hydrocarbons has been shut down and cannot perform maintenance functions without shutting down production. (d) are dependent upon mobility systems that are dependent upon lines connected to the surface to provide power and control, that use batteries that require recharging by surface systems or conveying units, or batteries of limited duration (e) are dependent upon the use of behavior based artificial intelligence software systems. Prior art tools require rigs for mobility and power or surface control systems to actuate permanently wired downhole systems which are very expensive or that are based upon using artificially based control systems with tools that require wireline connected surface control units that are subject to breaking or require shutting down production with the accompanying loss of income.
The present invention addresses some of the above noted needs and problems with prior art downhole tools and provides a robotic device that (a) does not require any connections to the surface by wire, umbilical, or other means for its operation (b) has a control system that allows the coordination and cooperation with other associated autonomous systems (c) has specific software programs written before entering the well in common languages such as C++ designed to control all specific functions required for work, (d) has the ability to perform maintenance functions in the conduit while hydrocarbons are flowing by past it and while the force of the flow of the fluids to generate power for operations using turbines or parachutes and bellows for mobility upward and braking in a downward direction, can identify conditions in the well that require action to be taken for optimizing flow and can take appropriate action and then report the action taken the next trip to the surface.
Our invention is a Robot Locomotion Using Inch Worm And Iris Drives to achieve energy efficiency enabling the robot to perform for longer periods of time in the well bore.
It has been recognized that it is desirable to reduce the cost of servicing oil and gas wells in remote locations and at offshore sites. Wells at such sites are often drilled at highly deviated angles, and many are horizontal. One of the major costs in the performance of these services is the rig that must servicing transport equipment through the well. Both the rental cost of the rig and the disruption of production during servicing are expensive. The industry thus seeks a means of servicing wells that eliminates the need for a rig to be continuously attached to the well during servicing, and a means to keep some production flowing during the operations.
In U.S. Pat. No. 5,947,213 and No. 6,026,911 and No. 6,112,8098 a robotic means is disclosed for lowering an apparatus into the well and conducting servicing operations. In its current embodiment, this technique involves a tractor that employs bicycle style chains asserted against the walls of the casing or tubing with strong springs or Beilville washers. However, this technique is necessarily less than 40 percent efficient because of friction of the gears and chain links. The robot is operated from a battery supplying energy for transport, conduction of services, and to power measurement instruments aboard the robot. The robot can only move through pipes whose radius does not change more than 40%.
A technique is described that employs a robotic means of lowering servicing and measurement equipment into a well and removing that equipment from the well upon completion of services. This system has more than double the energy efficiency because it uses different means of raising and lowering itself. In fact the present invention uses a combination of three types of locomotion.
First is an “inch-worm” technique wherein a clamp is asserted against the casing (or tubing) wall using hydraulic or other power means. An arm is then extended up (or down), and clamps at the end of the arm are engaged against the casing wall. The lower (or higher, respectively) clamp is then released and the arm is retracted to bring the unengaged clamps close to the engaged clamps. This motion is repeated resulting in progressive movement through the well bore.
The clamps at the top and bottom of the inchworm can also be configured to serve as guides and centralizing mechanisms. This will keep the tool aligned in the center of the well so that the tool does not rub on the walls. This will also aid in the other energy conserving transport modes described below.
Another means to permit low energy downward travel is to dither the force on the arms in order to permit limited and controlled slippage of the arms against the walls of the casing (or tubing) in water or oil wet wells. Acceleration sensors can be used to identify that the tool is falling in the well and to increase or decrease force against the sidewall to retard or permit more slippage. Use of the upper and lower clamps as guide and centralizing mechanisms will permit greater control of the dithering to control free-fall of the tool.
The third means can be used in wells with liquid phase materials in the well bore. It uses an iris-like device similar to the light restricting function performed in a photographic camera aperture setting device, the diameter of which can be controlled by sensors on the robot. The iris normally extends beyond the outside diameter of the tool, and its extent can be controlled by actuators disposed in the tool and operated by electric or other power sources. For downward motion, the iris is extended to reduce the annulus between the outside diameter of the iris and the inside diameter of the casing (or tubing) to the point were the fluid friction keeps the robot from accelerating its downward speed. Thus, with well-conditioned control of the iris diameter, the robot can fall downward until it reaches a horizontal part of the hole, a mechanical obstruction in the well, or until it reaches a predetermined downhole location. In this mode, energy consumption is very small compared to a tractor or even “inch-worm” design, because only the friction in the iris extension mechanism needs to be overcome.
Use of the upper and lower clamps as guides and centralizing mechanisms will permit better control of the fall (or rise—see below) of the tool by fluid flow. The centralizer can also permit sufficient control so that lift and fall can also be used in gas producing wells.
If there is upward flow of liquids in the well, the iris can be used to lift the robot out of the well after the mission is completed. Upward movement can use the same control system but with a smaller annulus between the iris outer diameter and the casing (tubing) inner diameter.
Combining the “inch-worm” drive with liquid conveyance will result in significant power savings. Downhole power, whether electric, hydraulic, or other, is ultimately supplied by batteries disposed in the tool. The largest cost on any downhole mission is the cost of the lithium batteries (which are currently the state-of-the-art in downhole batteries), hence, significant power savings translates directly to cost savings. Even if only the “inch worm” drive is used, it uses less energy than a chain drive because it has much lower friction losses such as the power going into the chain.
A final method of energy efficiency will be the use of a turbine driven electrical generator located in the tool that can be used to recharge rechargeable batteries in wells with liquid flow. If the tool is waiting in a flowing well, and it is clamped to the sidewall, a turbine and generator can recharge batteries to provide additional energy for extending or completing a down-well mission. Such a system could also be used during downward travel of the tool when an iris or dithered slippage is being employed.
The Capabilities of the Downhole Tool encompass all activities necessary for the management and maintenance of well throughout their life cycle.
A downhole tool has a capability for servicing wells that are drilled and completed at high angles and using multi-lateral branches to enhance oil and gas recovery. Such highly deviated wells are expensive to service. The robotic tool described above reduced the cost of servicing such wells because it does not require a rig stationed over the well during the servicing. In addition, in wells that are producing hydrocarbons, production can be continued (at some reduced rate) during passage of the robot through the well because the robot does not occupy the entire diameter of the well.
An important capability is to navigate along the correct branch of a multi-lateral completion. The tool design includes articulation so that part of the tool can move in a direction other than the principal path followed to get to a particular depth in the well. Then sensors in the tool are used to identify optional directions to be taken. Information preprogrammed into the computer control system of the tool use the data from the sensors to set the new direction for the tool to follow.
The tool further includes sensors to establish its current position in the well based on recognition of features of the well construction that are also described in a suitable form for the downhole computer. The computer then uses a pattern recognition routine in order to track its position based on a map of the well also loaded into the downhole computer memory.
The tool also includes mechanical actuators and other devices for performing operations on downhole hardware. Thus the tool can open and close valves, set packers, set bridge plugs, and conduct other operations needed to enhance productivity of the well.
The tool can convey sensors to assess performance of the well and to measure properties of the formation behind the casing. Such sensors may include gamma ray, neutron sensors, electrical, acoustic, and other electromagnetic sensors as may be understood by those skilled in the art of well logging.
In some embodiments, the tool can be used to convey perforating guns and to cause those guns to be discharged at controlled locations in the well. By using the depth correlation software described above, the tool can convey a perforating gun to the correct location, and it can deploy mechanical devices to constrain the gun to remain stationary until a command is provided to fire the guns. This capability allows the robot to move away from the gun during the time the gun is fired, and thereby the robot is not damaged by the percussive forces generated by the firing of the gun. After firing the gun, the robot can return to retrieve the empty gun, or it can leave the gun in place as defined by the configuration of the gun.
Another capability of the tool is that it may be configured to permit either unidirectional or bidirectional communication with the surface by means of electronic, acoustic, or mechanical pulsing. This capability will make it possible for a person to review data collected by the tool in preparation for performing a mechanical service or for perforating. Often, a review of the collar or gamma ray log is highly desirable prior to firing a perforating gun, and a bidirectional communications system will enable such a check on the tool location.